We all know of the Doppler Shift from the changing sounds of sirens in big cities even though we might not have been able to truly get our head around it in school science lessons. Surprisingly perhaps, first descibed in 1842 by the Austrian physicist Christian Doppler it explains how the wave form changes with the relative positions of e.g. police car and observer. (it is not of course exclusive to sound. The study of light wave Doppler Shifts have taught us a lot about our universe...). The received sound frequency is only 'accurate' or identical at the instant the car passes us.
The People Doppler Shift is much the same. We hear a lot about people before we meet them. A lot if not all of this information is distorted. In much of lIfe this can be self-fulfilling: we are 'told' someone is an under performer and then we act toward them as if that is true (so often done at school and college of course ...). And as the person walks away we distort the record of the conversation again, often turning it into gossip. The only way we really get to the 'true' person is to look them in the eyes and have a proper 'seek to understand' conversation. Tough? Oh, yes. Worth while? Absolutely.